This invention relates to a dental handpiece having a cleaning unit for causing clean gas or liquid to be passed through a gas supply passage for a turbine, a liquid supply passage for rising liquid or a chip-scattering gas supply passage for enabling the dental treatment to be performed under hygienic conditions.
There has hitherto been employed for dental treatment a dental handpiece fitted with a dental grinding tool, such as a bur, a point or a disc, for grinding or polishing teeth. The dental handpiece has a driving device, such as a turbine blade adapted for being rotated under air pressure in the inside of a turbine head. The dental handpiece also has an air supply passage for supplying air under pressure, a water passage for the rinsing water for rinsing teeth and a chip-scattering air supply passage for supplying air to scatter off cut chips or tooth debris on the downstream side of the turbine head. The driving device is adapted for driving a tooth cutting implement fitted with a cutting end. For dental treatment, such tooth cutting implement is selected which has a cutting end of a pre-set shape and size suited to the position or shape of the site of treatment or the object of treatment, and is exchangeably mounted at a tool head part of the turbine head.
However, with the above-described conventional dental handpiece, since air in a treatment room or tap water is directly introduced into the air supply passage for a turbine, the chip-scattering air supply passage or into the rinsing water supply passage and thence into the oral cavity of a patient, dental treatment cannot be performed under hygienic conditions if water or air or the inside of the piping connecting to the passages is contaminated.
On the other hand, with the dental handpiece in which when the supply of water under pressure during dental treatment is to be discontinued, the water under pressure is temporally sucked by e.g. a pull-back control valve to prevent dripping of the water, so that the water used for rinsing the oral cavity of the patient tends to flow back into the air discharge passage or the water supply passage to contaminate the inside of the piping.